2" shower drain position problem

I am adding a shower, toilet and sink to my unfinished basement. My question/problem relates to my shower. I am adding a Maax "Premium" shower kit (model K3874F-W05). Before construction I took the base dimensions off the box which said the 2" shower drain is 12" by 12" off the walls. See pic off of the box sticker:

Other diagrams on the box showed the panels being installed against wallboard (no studs visible):

I therefore assumed I'd have my 1/2" drywall and cement board all in place before adding the shower base and walls so I added an extra 1/2" to the dimensions. With my 1/2" cement board in place, the drain perfectly matches up at 12" by 12" assuming the shower base goes against the cement board. See pic of my basement where you can see the extra 1/2" measurement line:

Here's the problem... As I start to dive into the project, I sadly learn that the base actually goes directly against the studs and the rest of the shower panels attach to the cement board. See pic from inside the manual where they show the wallboard "cut out" to accomodate the shower base:

As you can imagine, in order to attach the shower base to the studs, my 2" PVC drain is no where near to center of the base drain. To fix this, I think my options are...

Add an extra 1/2" of OSB around both walls that surround the tub. This, I think is going to be a pain, because one wall is about 8 feet and the other about 4 feet. I would need to push both walls out a 1/2", move my electrical boxes out a 1/2", deal with an extra 1/2" for the prehung door, etc.

Dig up the concrete, cut the PVC down and install some type of coupler that will allow me to move the PVC over the little bit I need.

What options do you think might work best? If I go with the first option, I might be able to get away with just installing the extra 1/2" wallboard only around the 38" shower area and then hope I can trim around the shower wall edges. If I go with the second option, I don't know what type of coupler might exist that would give me the flexibility to move the pipe over.

Don't mess with the concrete, there are far easier ways to make up the dif.

I'd shim all the studs in the shower area or add another layer of cementboard just in the shower area. Use trim (a quarter-round or something) at the corner of the shower to transition down to the 'normal' bathroom wall.